Synthetic copolymer (AM/AMPS/DMDAAC/SSS) as rheology modifier and fluid loss additive at HTHP for water‐based drilling fluids

Synthetic copolymers as filtrate reducers for water‐based drilling fluids (WBDFs) are difficult to meet the needs of drilling engineering only by changing the type and proportion of functional groups of copolymers, especially under ultra‐high temperature and high salinity. In this study, an anionic terpolymer (named PSDI) with rigid side chain was synthesized using sodium p‐styrenesulfonate, N, N‐Dimethylacrylamide, and itaconic acid by free‐radical copolymerization. The chemical structure of PSDI was characterized by Fourier transform infrared spectroscopy and 1H‐NMR spectrum. The high‐temperature/high‐pressure filtration loss (FLHTHP) and the American Petroleum Institute filtration loss (FLAPI) of the WBDFs containing 1.5 wt/vol% PSDI were 35.0 and 17.0 ml after thermal rolling at 240°C for 16 h, respectively. The FLHTHP and FLAPI of the WBDFs containing saturated NaCl were with control of 60.0 and 12.0 ml. The FLAPI of WBDFs containing 1.5 wt/vol% CaCl2 reduced to 6.0 ml. Results indicate that the addition of PSDI can improve the anti‐high‐temperature performance and resistance to salt and calcium contamination of WBDFs. Results of rheological tests through fitting four rheological models suggest that rheological parameters can be improved as a result of forming the spatial network structure between the PSDI and bentonite flakes.

Section: Resultsmentioning

confidence: 99%

Section: Filtration Property Of the Wbdfsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Terpolymer with rigid side chain as filtrate reducer for water‐based drilling fluids

Yang

Liu

et al. 2020

NovelN,N‐dimethylacrylamidecopolymer containing multiple rigid comonomers as a filtrate reducer inwater‐baseddrilling fluids and mechanism study

Wang

Jiang

Yang

et al. 2021

Ultra‐high temperature dramatically deteriorates rheological properties and filtration performance of water‐based drilling fluids (WBDFs), especially for a salt‐gypsum formation that greatly restricts the application of WBDFs in ultra‐deep well drilling operations. Hence, the research in this article used an anionic copolymer (DANS) prepared by N, N‐dimethylacrylamide, 2‐acrylamide‐2‐methylpropanesulfonic acid, N‐vinylpyrrolidone, and sodium 4‐styrenesulfonate as an anti‐ultra‐high temperature and anti‐salt contamination filtrate reducer. Due to its multiple bulky cyclic structures in the side chain, DANS exhibits excellent thermal stability in the thermal gravimetric, rheological, and filtration tests. By adding 1.0 wt% DANS, the American Petroleum Institute (API) filtration volume of sodium bentonite‐based fluids (SBT‐BFs) decreased from 56.0 to 9.2 ml after aging at 240°C. Even under both 20 wt% NaCl contamination and 240°C aging, SBT‐BFs with 2.0 wt% DANS could maintain a filtration volume of 9.4 ml, whereas SBT‐BFs without DANS reached a filtration volume of 203.0 ml. The possible filtration control mechanism of DANS was further investigated via the Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), ζ potential, particle size distribution, filter cake micro‐morphology, and transmission electron microscopy (TEM). Confirmed by FTIR and AFM results, the effective adsorption was formed between DANS and bentonite even under a high‐salinity environment. Thus, a firm “dot net” structure formed by bentonite/DANS was observed by TEM, significantly improving the colloidal stability, dispersibility, and filter cake compactness of SBT‐BFs. Finally, by utilizing DANS as the core treatment agent, a high‐density WBDFs system with a temperature resistance of 240°C and a salt‐tolerance of 20 wt% has been successfully prepared.

Synthesis and performance evaluation of water‐absorbing resin coated with polymethyl methacrylate as a lost circulation material

Bai

Deng

Yan

et al. 2023

Lost circulation will cause huge economic losses every year. In order to effectively reduce the harm of lost circulation to drilling, it is particularly important to use reasonable and efficient lost circulation materials (LCM). As a kind of water‐absorbing, expandable and deformable LCM, water‐absorbing resin can adapt to holes and cracks of different sizes. In this study, a kind of encapsulated water‐absorbing resin LCM (PMMA/PNAD) was proposed. The water‐absorbing resin is synthesized by acrylamide (AM), 2‐acrylamide‐2‐methyl‐propane sulfonic acid (APMS) and diallyl dimethyl ammonium chloride (DMDAAC) as reaction monomers through aqueous solution polymerization. The shell material is polymethylmethacrylate (PMMA), which is coated on the surface of the water‐absorbing resin by oil phase separation method. The results of the experimental evaluation indicate that the water‐absorbing resin possesses robust water‐absorbing and swelling properties, which significantly affect the rheological properties of the drilling fluid. However, the coated shell can effectively mitigate the impact of the absorbent resin on the drilling fluid. Under the formation environment of 100°C or 2 Mpa, the shell can soften or break to release the absorbent resin. The lost circulation control performance test results show that PMMA/PNAD has good pressure bearing capacity, and can still maintain good lost circulation control at 6.9 Mpa.